“Hardfacing” is a technique which involves applying a layer of hard material to a substrate for the purpose of increasing the wear and corrosion resistance of the substrate. The use of this technique has increased significantly over the years as industry has come to recognize that substrates of softer, lower, cost material can be hardfaced to have the same wear and corrosion resistance characteristics as more expensive substrates of a harder material.
Hardfacing involves the deposition of a hard layer by welding or thermal spraying. Conventional weld hardfacing is accomplished by oxyfuel welding (OFW), gas tungsten arc welding (TIG), gas metal arc welding (GMAW), shielded metal arc welding (SMAW), submerged arc welding (SAW), and flux-cored arc welding (FCAW). Plasma transferred arc (PTA) hardfacing and laser beam hardfacing can also be used.
Most prior hardfacing materials that are harder than silicious earth materials are brittle and have a tendency to crack. These hardfacing materials are alloys which belong to a well-known group of “high Cr-irons” and their high abrasive resistance is derived from the presence in the microstructure of the Cr-carbides of the eutectic and/or hypereutectic type. In the as-welded condition, whatever the precautions taken, these hardfacing overlays always show a more or less dense network of cracks.
In view of the present state of hardfacing technology, it would be highly desirable and advantageous to provide an electrode to form a hardfacing alloy composition having a microstructure of high abrasive resistance capable of being weld deposited without cracks to withstand the conditions of use. Furthermore, it is desirable to provide an electrode to form a high chromium welding metal alloy system for use as a hardfacing surfacing on metal components that are subjected to high thermal and mechanical stresses.